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目的探讨在胰岛素诱导动脉粥样硬化发生的过程中,雌激素受体α(estrogen receptorα,ER-α)的作用。方法 18周龄Apoe/Lepr基因双敲小鼠按随机数字表法分为对照组和实验组(4 IU胰岛素组),每组4只。HE染色及免疫组化观察小鼠血管动脉斑块形成及α-平滑肌肌动蛋白(smooth muscle actin-α,α-SMA)、ER-α的表达。2用胰岛素及甲基化转移酶抑制剂干预大鼠血管平滑肌细胞,采用RT-PCR及Western blot检测DNA甲基化酶、ER-α的表达,划痕实验及流式细胞仪检测ER-α对血管平滑肌细胞增殖的影响。结果 1实验组小鼠血管出现动脉斑块,免疫组化结果显示α-SMA、ER-α表达降低(P<0.05)。2与对照组比较,胰岛素处理后血管平滑肌细胞中DNA甲基化酶的mRNA与蛋白表达升高(P<0.01),而ER-α表达下降(P<0.01),甲基化酶抑制剂可以消除这种差异,高表达ER-α后,划痕实验及流式细胞仪检测结果显示血管平滑肌细胞增殖减慢(P<0.05)。结论胰岛素通过促进DNA甲基化酶的表达,诱导ER-α基因甲基化,使ER-α表达下降,最终导致动脉粥样硬化的发生。
Objective To investigate the role of estrogen receptor α (ER-α) in the process of insulin-induced atherosclerosis. Methods 18-week-old Apoe / Lepr gene knock-out mice were divided into control group and experimental group (4 IU insulin group) according to random number table. The expression of vascular smooth muscle actin-α (α-SMA) and ER-α in mice was observed by HE staining and immunohistochemistry. The effects of insulin and methyltransferase inhibitor on vascular smooth muscle cells were detected by RT-PCR and Western blot. The expression of ER-α, DNA methylation and ER-α were detected by scratch assay and flow cytometry On the proliferation of vascular smooth muscle cells. Results 1 The arterial plaque appeared in the experimental group and the expression of α-SMA and ER-α was decreased by immunohistochemistry (P <0.05). 2 Compared with the control group, mRNA and protein expression of DNA methylase increased (P <0.01) and ER-α expression decreased (P <0.01) in insulin-treated vascular smooth muscle cells, and methylase inhibitor Elimination of this difference, high expression of ER-α, scratch test and flow cytometry results showed that the proliferation of vascular smooth muscle cells slowed down (P <0.05). Conclusion Insulin can induce the methylation of ER-α gene and decrease the expression of ER-α, leading to the development of atherosclerosis by promoting the expression of DNA methylase.